794
FNCA52 TJSJ 210730
FWFSJU
FIRE WEATHER PLANNING FORECAST FOR PUERTO RICO
NATIONAL WEATHER SERVICE SAN JUAN PR
330 AM AST THU MAY 21 2026
DISCUSSION
INCREASED MOISTURE COULD PREVENT RH VALUES FROM DECREASING BELOW
THRESHOLD VALUES FOR PROLONGED PERIODS; HOWEVER, RAINFALL SHOULD
AGAIN REMAIN LIMITED ACROSS THE SOUTHERN PLAINS, ALLOWING
RELATIVE HUMIDITY TO DROP TO CRITICAL FIRE WEATHER THRESHOLDS IN
THE REGION. ADDITIONALLY, SUSTAINED WINDS OF 15 TO AROUND 20 MPH,
WITH HIGHER GUSTS, COMBINED WITH ELEVATED KBDI VALUES, WILL FAVOR
THE RAPID SPREAD OF WILDFIRES ACROSS THE SOUTHERN COASTAL PLAINS.
THE LOW 7-DAY PERCENT OF NORMAL RAINFALL WILL ALSO PERSIST ACROSS
THE SOUTHEASTERN COASTAL PLAINS. FIRE MANAGEMENT PARTNERS ARE
ONCE AGAIN URGED TO REMAIN VIGILANT.
PRZ014-212000-
SOUTHEAST COASTAL PLAINS-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER MCLEAR PCLDY PCLDY
PRECIP TYPE SHOWERS SHOWERS SHOWERS
CHANCE PRECIP (%) 10 50 50
TEMP (24H TREND) 88 (+1) 72 (-2) 89
RH % (24H TREND) 49 (-5) 91 (+8) 52
WIND 20FT/EARLY(MPH) E 17 E 13 E 14
WIND 20FT/LATE(MPH) SE 17 E 12 E 17
MIXING HGT(FT-AGL/MSL)5700 5030
TRANSPORT WND (MPH) E 18 E 17
VENT RATE (KT-FT) 91200 75450
DISPERSION 5 5
DSI 6 5 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
PRZ015-212000-
SOUTHERN HILLS-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER MCLEAR PCLDY PCLDY
PRECIP TYPE SHOWERS SHOWERS SHOWERS
CHANCE PRECIP (%) 10 40 40
TEMP (24H TREND) 86 (+3) 68 (-3) 85
RH % (24H TREND) 58 (-8) 98 (+10) 62
WIND 20FT/EARLY(MPH) E 13 E 13 E 12
WIND 20FT/LATE(MPH) SE 13 E 13 E 12
MIXING HGT(FT-AGL/MSL)6400 5620
TRANSPORT WND (MPH) E 17 E 16
VENT RATE (KT-FT) 96000 78680
DISPERSION 5 5
DSI 6 4 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
PRZ016-212000-
NORTH COASTAL PLAINS-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER PCLDY PCLDY PCLDY
PRECIP TYPE SHOWERS SHOWERS TSTMS
CHANCE PRECIP (%) 40 40 60
TEMP (24H TREND) 89 (+1) 72 (-1) 88
RH % (24H TREND) 56 (-6) 97 (+7) 61
WIND 20FT/EARLY(MPH) E 14 E 16 E 14
WIND 20FT/LATE(MPH) E 20 E 12 E 19
MIXING HGT(FT-AGL/MSL)6210 4840
TRANSPORT WND (MPH) E 17 E 14
VENT RATE (KT-FT) 93150 58080
DISPERSION 5 5
DSI 6 5 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
PRZ017-212000-
NORTHERN HILLS-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER PCLDY PCLDY PCLDY
PRECIP TYPE TSTMS SHOWERS TSTMS
CHANCE PRECIP (%) 50 30 60
TEMP (24H TREND) 87 (0) 69 (-2) 87
RH % (24H TREND) 57 (-5) 97 (+5) 64
WIND 20FT/EARLY(MPH) E 13 E 12 E 12
WIND 20FT/LATE(MPH) E 18 E 9 E 16
MIXING HGT(FT-AGL/MSL)7570 6010
TRANSPORT WND (MPH) E 14 E 12
VENT RATE (KT-FT) 90840 60100
DISPERSION 5 5
DSI 6 4 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
PRZ018-212000-
WEST COAST-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER PCLDY MCLEAR PCLDY
PRECIP TYPE TSTMS SHOWERS TSTMS
CHANCE PRECIP (%) 30 20 50
TEMP (24H TREND) 90 (+1) 71 (-2) 90
RH % (24H TREND) 57 (-6) 94 (+6) 62
WIND 20FT/EARLY(MPH) E 14 E 13 E 14
WIND 20FT/LATE(MPH) E 14 E 12 E 14
MIXING HGT(FT-AGL/MSL)5440 4860
TRANSPORT WND (MPH) E 14 E 13
VENT RATE (KT-FT) 65280 53460
DISPERSION 5 5
DSI 6 5 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
PRZ019-212000-
EASTERN INTERIOR-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER PCLDY PCLDY PCLDY
PRECIP TYPE SHOWERS SHOWERS SHOWERS
CHANCE PRECIP (%) 30 60 40
TEMP (24H TREND) 87 (+3) 69 (-3) 87
RH % (24H TREND) 59 (-6) 99 (+9) 62
WIND 20FT/EARLY(MPH) E 14 E 14 E 14
WIND 20FT/LATE(MPH) E 13 E 14 E 14
MIXING HGT(FT-AGL/MSL)6930 5700
TRANSPORT WND (MPH) SE 16 E 16
VENT RATE (KT-FT) 97020 79800
DISPERSION 5 5
DSI 6 4 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
PRZ022-212000-
LUQUILLO MOUNTAIN RANGE-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER PCLDY PCLDY PCLDY
PRECIP TYPE SHOWERS SHOWERS SHOWERS
CHANCE PRECIP (%) 40 60 40
TEMP (24H TREND) 83 (+4) 68 (-3) 83
RH % (24H TREND) 64 (-9) 100 (+7) 67
WIND 20FT/EARLY(MPH) E 12 E 12 E 12
WIND 20FT/LATE(MPH) E 12 E 12 E 12
MIXING HGT(FT-AGL/MSL)4850 3600
TRANSPORT WND (MPH) SE 17 E 17
VENT RATE (KT-FT) 72750 54000
DISPERSION 5 5
DSI 6 6 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
PRZ023-212000-
CENTRAL MOUNTAIN RANGE-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER PCLDY PCLDY PCLDY
PRECIP TYPE SHOWERS SHOWERS TSTMS
CHANCE PRECIP (%) 30 30 60
TEMP (24H TREND) 85 (+4) 66 (-3) 84
RH % (24H TREND) 59 (-9) 98 (+7) 67
WIND 20FT/EARLY(MPH) E 11 E 8 E 10
WIND 20FT/LATE(MPH) SE 11 E 8 E 10
MIXING HGT(FT-AGL/MSL)7860 6700
TRANSPORT WND (MPH) SE 10 E 12
VENT RATE (KT-FT) 70740 67000
DISPERSION 5 5
DSI 6 2 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
PRZ024-212000-
CAYEY MOUNTAIN RANGE-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER MCLEAR PCLDY PCLDY
PRECIP TYPE SHOWERS SHOWERS SHOWERS
CHANCE PRECIP (%) 10 60 40
TEMP (24H TREND) 83 (+3) 68 (-2) 82
RH % (24H TREND) 64 (-8) 100 (+7) 67
WIND 20FT/EARLY(MPH) E 12 E 11 E 11
WIND 20FT/LATE(MPH) E 12 E 11 E 11
MIXING HGT(FT-AGL/MSL)5660 4880
TRANSPORT WND (MPH) E 17 E 16
VENT RATE (KT-FT) 84900 68320
DISPERSION 5 5
DSI 6 4 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
PRZ025-212000-
VIEQUES-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER PCLDY PCLDY PCLDY
PRECIP TYPE SHOWERS SHOWERS SHOWERS
CHANCE PRECIP (%) 30 50 20
TEMP (24H TREND) 89 (+3) 77 (+1) 88
RH % (24H TREND) 56 (-7) 85 (+1) 59
WIND 20FT/EARLY(MPH) E 17 E 19 E 18
WIND 20FT/LATE(MPH) E 16 E 19 E 17
MIXING HGT(FT-AGL/MSL)4110 3450
TRANSPORT WND (MPH) E 21 E 23
VENT RATE (KT-FT) 73980 69000
DISPERSION 5 5
DSI 6 6 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
PRZ026-212000-
CULEBRA-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER PCLDY PCLDY PCLDY
PRECIP TYPE SHOWERS SHOWERS SHOWERS
CHANCE PRECIP (%) 20 40 20
TEMP (24H TREND) 90 (+3) 77 (0) 90
RH % (24H TREND) 56 (-7) 86 (+3) 56
WIND 20FT/EARLY(MPH) E 17 E 18 E 18
WIND 20FT/LATE(MPH) E 17 E 18 E 17
MIXING HGT(FT-AGL/MSL)4060 3420
TRANSPORT WND (MPH) E 22 E 23
VENT RATE (KT-FT) 77140 68400
DISPERSION 5 5
DSI 6 6 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
PRZ027-212000-
SOUTHWEST COASTAL PLAINS AND MONA ISLAND-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER MCLEAR MCLEAR PCLDY
PRECIP TYPE SHOWERS SHOWERS SHOWERS
CHANCE PRECIP (%) 10 10 20
TEMP (24H TREND) 90 (+1) 73 (-2) 90
RH % (24H TREND) 48 (-7) 88 (+9) 51
WIND 20FT/EARLY(MPH) E 19 E 18 E 20
WIND 20FT/LATE(MPH) SE 20 E 17 SE 19
MIXING HGT(FT-AGL/MSL)5560 5040
TRANSPORT WND (MPH) E 21 E 21
VENT RATE (KT-FT) 100080 90720
DISPERSION 5 5
DSI 6 6 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
VIZ001-212000-
SAINT THOMAS AND SAINT JOHN-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER PCLDY PCLDY PCLDY
PRECIP TYPE SHOWERS SHOWERS SHOWERS
CHANCE PRECIP (%) 30 40 30
TEMP (24H TREND) 85 (0) 77 (0) 86
RH % (24H TREND) 63 (-1) 86 (+3) 62
WIND 20FT/EARLY(MPH) E 18 E 19 E 18
WIND 20FT/LATE(MPH) E 17 E 18 E 17
MIXING HGT(FT-AGL/MSL)4030 3400
TRANSPORT WND (MPH) E 22 E 23
VENT RATE (KT-FT) 76570 68000
DISPERSION 5 5
DSI 6 6 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
VIZ002-212000-
ST CROIX-
330 AM AST THU MAY 21 2026
TODAY TONIGHT FRI
CLOUD COVER PCLDY PCLDY PCLDY
PRECIP TYPE SHOWERS SHOWERS SHOWERS
CHANCE PRECIP (%) 20 30 20
TEMP (24H TREND) 88 (+2) 77 (+1) 88
RH % (24H TREND) 59 (-5) 87 (+4) 61
WIND 20FT/EARLY(MPH) E 16 E 18 E 18
WIND 20FT/LATE(MPH) E 17 E 18 E 17
MIXING HGT(FT-AGL/MSL)4870 4550
TRANSPORT WND (MPH) E 21 E 22
VENT RATE (KT-FT) 87660 86450
DISPERSION 5 5
DSI 6 6 6
RH RECOVERY EXCELLENT
REMARKS...NONE.
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